Having a single benchmark for spelling, grammar, and universal readability makes the whole series more accessible.
Amen. Especially since consistent spelling makes grep(1) a useful tool. (Consistent use of acronyms/abbreviations also helps, but that's a different discussion.)
I do question whether that benchmark should be "standard American" (using CMoS as a proxy) or "whatever is most understandable for our audience"; but the latter lacks a formal spec, and we do like our formal specs.
Chicago doesn't dictate spelling, does it? (My copy went AWOL a decade ago.) Regardless, the RFC series originated in the US (aka 'America' for this conversation), so American spelling wins by fiat. I can live with that, as any other rational(e) person can.
And whilst I take divers gratification petitioning cheques from my American comrades, for goods forthwith provided, I will accept a check.
As long as it clears the banque. --lyndon